1. Field of the Invention
The present invention relates to an improvement of a lighting device used in an interior of a vehicle.
2. Description of the Related Art
In a lighting device for an interior of a vehicle, since a map lamp for lighting a part near the hand of a person riding on the vehicle or a room lamp for lighting a wide area in the interior of the vehicle is provided in a restricted area such as a ceiling in the interior of the vehicle, the lamp needs to be compact and thin. For instance, patent literature 1 discloses a lighting device using an LED lamp as a light source of a map lamp. Further, patent literature 2 discloses a room lamp including an LED lamp and a light guide plate to convert the light of the LED lamp to a planar light by the light guide plate and light an interior of a vehicle.    Patent literature 1: JP-A-2008-53065    Patent literature 2: JP-A-2000-127847
In the structure of the patent literature 1, since the LED lamp is a point light source and its directivity is higher than that of a bulb lamp, an area (glare) where a luminance is excessively high may occasionally generated to dazzle a person riding on the vehicle. Further, in the LED lamp that the light of an LED element is mixed with a fluorescence by a fluorescent material dispersed in a seal member to radiate the light of a prescribed color, the light of the LED element is not sufficiently mixed with the fluorescence so that a color shade or a color separation may arise. Further, when such a radiated light of the LED lamp is converged by a lens, the color shade or the color separation is more outstanding due to the aberration of the lens. Since the map lamp is used when the person riding on the vehicle looks at a map to light a spot on the map, such glare, color shade and color separation especially cause a problem. Further, when the lighting device is externally observed, the LED lamp is visually recognized, so that an outward appearance is not good. Further, since the structure of the patent literature 1 separately includes the light source of the map lamp and the light source of the room lamp, the number of parts is increased, an attaching operation is complicated and a cost is undesirable. As one of countermeasures for solving the problems, such a structure as in the patent literature 2, that is, the structure in which the LED lamp and the light guide plate are used to form the planar light may be supposed to be applied to the map lamp. However, since the light of the map lamp requires the directivity and the luminance higher than those of the light of the room lamp, when the light of the LED lamp as the point light source is simply converted into the planar light by the light guide plate, the directivity and the luminance necessary for the light of the map lamp cannot be obtained. Further, the structure of the patent literature 2 includes the map lamp and the room lamp integrally, however, since the directions of the lights irradiated therewith are different from each other, the light source parts thereof are separately provided. Therefore, controlling harnesses need to be managed by the light source parts respectively so that an attaching operation is complicated. Further, a labor for inspecting a product is increased. Further, since a heat radiating member needs to be separately provided as well as the harnesses, the number of parts is undesirably increased.